If you fast charge, Tesla will permanently throttle charging

[tga]

One of the sad takeaways from this thread for me personally is that an H battery may be problematic.. and -- you guessed it -- according to my VIN at least -- I have the dreaded H battery. sucks!

Are you looking at an H in the 10th digit? That encodes model year 2017, not battery type. I'm pretty sure they never encoded battery type/size in the VIN.

You need to turn the wheels hard to the left, then look at the battery sticker visible through the passenger side wheel well.

Note it's really part number and letter sub type code that matters (middle line on the sticker)
Mine says:
85kWh,400VDC
1014114-00-E
<serial number>

That's an E battery, but it would be different than 1014114-01-E, since the numeric part differs. You can only compare subtype code letters for the same base part number (this is Tesla's standard part numbering scheme, BTW).

 

[Galve2000]

Are you looking at an H in the 10th digit?

I'm looking at the 7th digit in my VIN which is H. I have a May 2015-build S85D that had the minor misfortune of being one of the last vehicles to roll off the line with 3G cellular service instead of LTE.

Shortly thereafter, Tesla started shipping cars with E as the 7th digit in the VIN most likely denoting "Electric" or "Every" (battery type) b/c they started shipping software limited 75s,(and software limited 90s, maybe??) but my car is just old enough to follow the original battery-naming convention.

You need to turn the wheels hard to the left, then look at the battery sticker visible through the passenger side wheel well.

I will do this at my earliest opportunity (my car is the the shop for replacement of a rear passenger quarter panel) but should be back in my hands sometime next week. Still, given the H in the 7th digit of my VIN I doubt I will be surprised by what I find.

That's an E battery, but it would be different than 1014114-01-E, since the numeric part differs. You can only compare subtype code letters for the same base part number (this is Tesla's standard part numbering scheme, BTW).

You lost me here. what is the difference between 00-E and 01-E and 02-E if such a thing exists? I thought the letter was all that mattered. BTW I don't disagree with you that the letter on the wheel well sticker definitively identifies the battery type. I am just saying that in my case -- with an early enough build -- the 7th digit of the VIN will suffice, and I have this all over my paperwork. no need to check the wheel well.

Interestingly, your car is older than mine. (I just noticed.) do you have an E in the 7th digit of your VIN?

 

[apacheguy]

I have never heard of an H pack for 85 kWh confígs. VIN is absolutely not reliable. Need to check battery sticker.

 

[tga]

Shortly thereafter, Tesla started shipping cars with E as the 7th digit in the VIN most likely denoting "Electric" or "Every" (battery type) b/c they started shipping software limited 75s,(and software limited 90s, maybe??) but my car is just old enough to follow the original battery-naming convention.

They have definitely changed the VIN encoding over the years, but for 2015, it looks like H for the 7th digit just means "High capacity battery," not battery version - See: https://teslatap.com/vin-decoder/

You lost me here. what is the difference between 00-E and 01-E and 02-E if such a thing exists? I thought the letter was all that mattered.

Just that the letter only matters in the context of the overall part number - you can't compare letters only. A 100kWh "A" pack is (should be) newer than an 85kWh "D" pack.

Interestingly, your car is older than mine. (I just noticed.) do you have an E in the 7th digit of your VIN?

Good point - there's hope for you - I have an H there too.

Also, my car was a CPO, so I can't guarantee it has its original pack.

 

[oktane]

Not much left to debate ... Tesla explains why it limits Supercharging speed after high numbers of DC charges

In a statement, Tesla explains that it is a software limitation to optimize for the best possible owner experience that’s within the limits of physics. Here’s the statement in full:

“The peak charging rate possible in a li-ion cell will slightly decline after a very large number of high-rate charging sessions. This is due to physical and chemical changes inside of the cells. Our fast-charge control technology is designed to keep the battery safe and to preserve the maximum amount of cell capacity (range capability) in all conditions. To maintain safety and retain maximum range, we need to slow down the charge rate when the cells are too cold, when the state of charge is nearly full, and also when the conditions of the cell change gradually with age and usage. This change due to age and usage may increase total Supercharge time by about 5 minutes and less than 1% of our customers experience this.

No *sugar* Tesla. Why don't you just replace 1% of the battery packs under warranty?

 

[Galve2000]

No *sugar* Tesla. Why don't you just replace 1% of the battery packs under warranty?

I fully agree with this.

More than that, I think the algorithm for "throttling" or restricting the OPs battery is being sloppy.

There is no way "frequent" charging at 45 kW is as bad as frequent charging at 90 kW or 115 kW. 45 kW is a little over double what that those who charge at 22 kW in europe or older 60 and 85 packs charge with dual chargers. And some of us charge this way on a nightly basis.


What I think is happening is that the algorithm does not differentiate between ChAdeMo DC charging (which currently maxes out at 50 kW IIRC) and Supercharging (which can be twice that powerful, or more) and I believe it should. B/C of his atypical usage of frequent ChAdemo charging the OP hit some sort of limit that is in place to protect from frequent 90 kW charging.

In my view, the OPs "supercharger counter" should be reset and his car monitored closely as a test case.

And if what I said above is not true, and all charging above a certain kW is detrimental to the battery, tesla needs to tell us what it is so we can figure out how to best care for our batteries.

I say this with particular interest as condo owner. I am lucky enough that my primary residence is in a sea of destination chargers so I am primarily charging at 8kW (208 V x 40 Amps) but the home I may retire to someday no such sea of level 2 chargers exists and I was hoping to use the new SC 13 miles away once a week or so as needed. Of course I have many, many miles to walk before happy retirement and there may be more level 2 charging options available to me by then. but i'm not holding my breath. even the nearby SC was a well-welcomed and very unexpected gift given that there was already a SC 20 miles from my future retirement home.

 

[stopcrazypp]

No *sugar* Tesla. Why don't you just replace 1% of the battery packs under warranty?

Why would they want to do that if just simply changing the charging algorithm slightly can prevent the need to replace those 1% of batteries?

 

[WarpedOne]

1% is 2000 batteries.
A battery costs $20k, total $40M, $0.20 per share

I say limit that algo!

 

[JRP3]

There is no way "frequent" charging at 45 kW is as bad as frequent charging at 90 kW or 115 kW.

There may actually be a way as I've pointed out previously in the thread. IF the lower charge rate is still high enough to cause undesirable side reactions in the cell AND the longer time spent charging allows more time for the side reactions to occur then it could be just as bad. I don't know if that's the case but it could be.

 

[David99]

I've compared the reduced 90 kWh battery charge rate to my 85 pack at a Supercharger and the 90 still charges faster. So it's not like the new batteries have a disadvantage. If anyone wants to trade, I'm happy to trade my 85 battery with a charge rate reduced 90. Any takers?

 

[thecloud]

I've compared the reduced 90 kWh battery charge rate to my 85 pack at a Supercharger and the 90 still charges faster. So it's not like the new batteries have a disadvantage. If anyone wants to trade, I'm happy to trade my 85 battery with a charge rate reduced 90. Any takers?

Are you saying that your 85 never sees a charging rate above 90-95kW anymore? (That isn't everyone's experience yet, so you may not be able to generalize to "older batteries have no advantage".) Would be great to see a comparison video with your 85 pack.

 

[wcfinvader]

106k miles and still charging at top speeds. 4B Lincoln, NE supercharger. We do have a loaner battery which appears to be new so this can be used as a data point as what should be the top capable speed on current batteries. Having said that we saw these speeds on our old battery before it was taken away from us.

 

[David99]

Are you saying that your 85 never sees a charging rate above 90-95kW anymore? (That isn't everyone's experience yet, so you may not be able to generalize to "older batteries have no advantage".) Would be great to see a comparison video with your 85 pack.

No, my pack starts at 116 kW but the tapers down much more than the new battery packs. To add a typical amount of energy to make it from Supercharger to Supercharger, the 90 pack is faster even though it never goes above 95 kW. Peak charge rate is not what matters. The only think that matters is how much energy is added in a given amount of time.
Look here comparing Supercharge speed 85 vs 90

 

[No2DinosaurFuel]

I've compared the reduced 90 kWh battery charge rate to my 85 pack at a Supercharger and the 90 still charges faster. So it's not like the new batteries have a disadvantage. If anyone wants to trade, I'm happy to trade my 85 battery with a charge rate reduced 90. Any takers?

Indeed you are correct. The old 85s would start higher but has a linear drop right off the bat. The 90s have a lower start point, unless you are around 30% in, but sustain it for pretty much the whole charge until around 55% at which most should be thinking of leaving.

While it is true your 85s is still slower than the 90s, I think most are complaining that they did not know of degradation if using dcfc often. For me I purposely held off buying a tesla because I read of the faster charging capability of the 90s. But now it seems that is even a wash.

What next? Tesla will probably tell me I need to upgrade to the 100D to avoid this problem. But I am sure there will be something else on wrong with that one. We just don't know about it yet.

 

[AmpedRealtor]

I've been giving this a lot of thought and I think I've boiled things down to a few important questions that I think need answers:

1. Is there an actual counter that increments each time you Fast Charge, if so, what is the threshold for throttling?
2. If a counter exists, does it differentiate between slower FC and Supercharging (CHAdeMO vs SC)? If not, why not?
3. If CHAdeMO, topping out at ~45kW is "bad" charging, where is the threshold of "safe" vs "bad?" 22kW? 30kw? We really need to know this.
4. If 45kW is "bad," then if I use CHAdeMO (or an SC) when my battery is @65 or 70% and charge to 90%, the current is much less than 45kW, is that now safe? And if so, why is the FC counted against me for throttling purposes?
5. If there is a known threshold between "good" and "bad" charging, can we have a slider to throttle fast charging to the "safe" zone? I would like to still use CHAdeMO regularly and if I could throttle it to 22kW or 30kw or whatever is deemed "safe," then I would prefer to do that.

I think these questions are the most pertinent to the end user that's not concerned with minutiae. These questions are what keeps the battery safe and can represent a "best practices" for longevity of the battery. A slider would also allow those not concerned with longevity to charge faster at the risk of their battery. The slider for maximum charge is already in the users face quite prominently, and the ommission of a slider for charge rate is pretty glaring in light of these discoveries. Heck, if it's better to charge my car at 5kW as opposed to 10kW, the slider would make that easy to do and a lot of people would be fine doing that if they have the time. Why not make that available?

You will never see Tesla providing this type of information. Tesla wants customers to charge to their heart's content and not to worry about it. Doing what you suggest will simply overcomplicate things and create a PR disaster for Tesla. Nope, not going to happen.

 

[David99]

Well my Supercharging speed (S85) has been reduced over time as well. From when it was new to now it's definitely slower and takes longer. They never told me about it. but let's assume I had known this before I bought the car. I would still have bought it and I would still have used it for just as many road trips knowing exactly that it would reduce the charge performance of my car.

I think the mistake is that some look at 95 kW charge power vs 120 kW. That suggests a 30% reduction in charge rate. The reality is different. They cap the peak rate but sustain a higher rate longer. The difference is not as much as the peak rate.

Way before the Model S, Tesla wrote on their blog that both high charge and discharge rates are bad for the battery. It's still up on their blog for everyone to read. They actually specifically say anything above 0.5C is bad. That's 45 kW.

Back in 2014, under the Supercharge FAQ was a question:

How often can I Supercharge? Is it bad for my battery?
Supercharging does not alter the new vehicle warranty. Customers are free to use the network as much as they like.

They avoid making a statement about the battery here, just refer to the warranty. The warranty doesn't cover degradation, though. But they so say it's fine to use it as often as we like. That's contradicting the blog post from several years before.

At a public talk Elon said the Supercharger rate is actually conservative (meaning they could charge faster), but they just don't know what the long term effect is on the battery, so they want to be on the safe side.

I think clearly Tesla is learning as they go and being a pioneer that's expected. I'm happy with my 85. I'd be even happier with a 90, and one way or another I would have bought the car back then with the knowledge I have now.

 

[jbdvm1988]

Purchased my S90D December 2016 with free lifetime supercharging. My battery part # is 1088790-00-A. I'm reading about an H battery. Can someone decode my part number to give me insight into the likelihood I've got a battery that may be throttled. Quite frankly I feel like a laboratory rat that got the "new" battery chemistry AND paid a premium for the free supercharging for life and now the chemistry is causing issues and lifetime supercharging may degrade the battery. Definitely a bummer!!!

 

[n2mb_racing]

Here is some info on P90D batteries and max power outputs (before the reductions):
Tesla Model S PxxxD(L) Comparisons (Responses)

But, I don't see yours on there. I'd guess it isn't limited yet, if you haven't supercharged a lot.

 

[thecloud]

No, my pack starts at 116 kW but the tapers down much more than the new battery packs. To add a typical amount of energy to make it from Supercharger to Supercharger, the 90 pack is faster even though it never goes above 95 kW. Peak charge rate is not what matters. The only think that matters is how much energy is added in a given amount of time.
Look here comparing Supercharge speed 85 vs 90

Thanks. Your graph in another thread really makes the throttling that you experienced quite clear.

What's not clear (to me, anyway) is whether this drop-off is initiated by the car or by the supercharger. In the thread I mentioned, it seems like it might be partially correlated with handle temperature, and moving to an unused stall gets the expected (sustained) charging speed again.

I agree that peak rate isn't what matters, but if you know where the peak rate is sustained and where it is expected to ramp up and down, you can plan to arrive at the supercharger with an optimal SOC to take advantage of it. It used to be the case that the peak rate was reached relatively quickly, and only ramped down as you filled up (remember the "filling a glass of water so you don't spill over" analogy?) Now we have different behavior being reported, and I think it's important to know whether an adjustment in our behavior is needed to minimize the time spent at each supercharger.

Haven't taken a trip requiring supercharger use for a few months, and have gotten a couple of software updates during that time. Will definitely be on the lookout for what charging rates I get in future.

 

[thecloud]

A quote from Tesla's Enable Supercharging page, which may or may not be relevant today:

When Supercharging is enabled, drivers can charge for no additional cost at any of Tesla’s expanding network of 120 kW Tesla Superchargers. Superchargers are external chargers designed to replenish over half a charge in 20 minutes.